1. Field of the Invention
The present invention relates to an integrated, modular, sub-assembly for the control of a pressure drop detector and excess speed governor for turbo machines.
2. Description of the Prior Art
It is known that fuel regulators for turbo machines comprise generally, a flow dispenser of which the upstream portion is connected to the outlet of a pump and the downstream portion to an injection circuit. A regulatory valve is placed either in a branch circuit from the line between the pump and the dispenser in the case of a volumetric pump, or in series between the pump and the dispenser, or between the dispenser and the user installation in the case of a centrifugal pump. A pressure drop detector is intended to provide a modulated pressure outlet Pmod as a function of the pressure drop PAm-PAv where PAm and PAv are pressures measured upstream and downstream of the dispenser, the output pressure Pmod acting on the regulatory valve to open or close the latter when the pressure drop varies, in order to keep the pressure drop constant. An excess speed governor is capable of taking into account the rotational speed of the turbo machine for which a threshold of excess speed is fixed so as to reduce the injected fuel flow into the user installation when this threshold is exceeded in order to avoid a possible runaway of the turbo machine.
French Pat. Nos. 2 180 484, 2 180 485 and 2 180 509, are all in the name of the present applicant, and illustrate what is now a conventional way of carrying out this kind of regulation in which all the regulation functions are distributed within a voluminous hydraulic block.
Since the time of filing of the applications leading to the grant of these patents, the tendancy of engine manufacturers has been to produce modular assemblies where each module fulfils one or two functions for the regulation assembly. This modular construction enables simplification in the operations to be undertaken, and thus their cost and further to produce miniaturized modules, which contributes to achieving the objective of reduction in the volume and of the weight of the engines and their accessories.
French Pat. Nos. 2 528 495 and 2 543 220, similarly in the name of the applicants, foresee the integration of the regulatory valve within the interior of the flow dispenser in order to produce a modular sub-assembly fulfilling these two functions.
U.S. Pat. No. 3,538,707 foresees for its part the modularization of a dispenser, of a regulatory valve, of a pressurization valve and of a valve subject to excess pressure by alignment of these devices, with furthermore the integration of the excess pressure valve within the pressurization valve.
The present invention has for its object to the production of a sub-assembly integrating two regulatory functions, namely the detection of pressure drop and governing of excess speed, while producing the combination of these two functions in a common device where a fixed sleeve of the pressure drop detector serves for the location of the movable shuttle valve of the excess speed governor in order to effect miniaturization of the modular sub-assembly.